Notwithstanding td’s input, it’s still not clear what actual problem was.
If it was a straightforward mechanical failure then the probability of a dual event is very remote like that of an improbable software malfunction – i.e. a failure rate as assumed for ETOPS.
However, if as intimated the engine experienced a ‘recoverable ice crystal encounter’ (ICE) then the subsequent shutdown could indicate damage greater than that assumed in the safety case for operations near such conditions.
Although the risk of a dual shutdown due to ICE damage has been accepted, this incident could question that judgement due to the apparent ineffectiveness of flight restrictions and by the extent, or crew's perception of whatever damage occurred, i.e a shutdown occurred when not expected, and the cause could have affected both engines simultaneously!
Some operators relate ICE with the tropics and have planned their operations to avoid these routes, but ICE is associated with large storms in a tropical air mass. Did this event, albeit in the N Atlantic, involve a tropical air mass, perhaps the remnants of a hurricane?